Another throttle body cleaning, Surging idle thread
09-11-2017, 12:45 PM
#62
New Member
And when/why did this issue start? Year? Mileage? Mods?
09-27-2017, 05:21 AM
#63
Anyhow, I found that the high idle was causing the PCV valve to open, pulling in additional air into the plenum and resulting in surging - and an idle that just wouldn't go down.
Solution for me was to disconnect the PCV tube at the plenum end and temporarily block it. This reduced the idle to ~850rpm and stopped any surging.
Perform an idle relearn using the usual methods making sure the parameters are all ok (so that the relearn sticks). Start and stop engine a couple of times to ensure the relearn has stuck, then reconnect the PCV line and re-perform the idle relearn.
Mine is back at 650rpm & 15deg BTDC at idle with nice clean TBs. (It was previously surging like a ***** between 1500-1800rpm...).
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pgs (12-19-2018)
09-27-2017, 02:42 PM
#64
Having the same issue as well. Here is a link to my thread with what I've done so far.
https://my350z.com/forum/engine-and-...ging-idle.html
As of today I haven't been able to fix this issue.
https://my350z.com/forum/engine-and-...ging-idle.html
As of today I haven't been able to fix this issue.
09-27-2017, 03:30 PM
#65
Could this be your lucky day? Try the PCV block method I mentioned above and let us know if it works for you! 
My assumption is that high idle is generally caused by higher than normal air flow. This is an obvious symptom of cleaning TBs... not so obvious for hurricanes passing. With our now higher idle speeds, the PCV is releasing crankcase pressure as it is expected to do at 1500-2000rpm but is certainly not supposed to do at a normal idle - hence the temporary blocking (just let the PCV vent to atmosphere while you do the relearns).
(Btw, I tried all you did & also pulled a couple of injector plugs as mentioned in this thread all to no avail.)
Cheers,
Guv
My assumption is that high idle is generally caused by higher than normal air flow. This is an obvious symptom of cleaning TBs... not so obvious for hurricanes passing. With our now higher idle speeds, the PCV is releasing crankcase pressure as it is expected to do at 1500-2000rpm but is certainly not supposed to do at a normal idle - hence the temporary blocking (just let the PCV vent to atmosphere while you do the relearns).
(Btw, I tried all you did & also pulled a couple of injector plugs as mentioned in this thread all to no avail.)
Cheers,
Guv
09-27-2017, 05:03 PM
#66
Hey Guy,
I'm glad that PCV block method worked for you! I just tried it with enthusiasm about 10 mins ago (it was already dark outside) but it did not work
Maybe I did it in a rush?
So I disconnected the hose that goes from the PCV valve on the passanger side valve cover to the intake manifold at the intake manifold connection. I plugged it, and then turned on the car. That didn't help, and the car behaved the same.
Then I just left the intake manifold connection unplugged (big vacuum leak) and when I turned on the car, the idle did drop a lot and the car seemed to want to die, but after a couple of second it revved up and started to do the dam surge again.
Did I do this right? wrong? any suggestions on how to do it in a better way?
I'm glad that PCV block method worked for you! I just tried it with enthusiasm about 10 mins ago (it was already dark outside) but it did not work
Maybe I did it in a rush?
So I disconnected the hose that goes from the PCV valve on the passanger side valve cover to the intake manifold at the intake manifold connection. I plugged it, and then turned on the car. That didn't help, and the car behaved the same.
Then I just left the intake manifold connection unplugged (big vacuum leak) and when I turned on the car, the idle did drop a lot and the car seemed to want to die, but after a couple of second it revved up and started to do the dam surge again.
Did I do this right? wrong? any suggestions on how to do it in a better way?
Could this be your lucky day? Try the PCV block method I mentioned above and let us know if it works for you!
My assumption is that high idle is generally caused by higher than normal air flow. This is an obvious symptom of cleaning TBs... not so obvious for hurricanes passing. With our now higher idle speeds, the PCV is releasing crankcase pressure as it is expected to do at 1500-2000rpm but is certainly not supposed to do at a normal idle - hence the temporary blocking (just let the PCV vent to atmosphere while you do the relearns).
(Btw, I tried all you did & also pulled a couple of injector plugs as mentioned in this thread all to no avail.)
Cheers,
Guv
My assumption is that high idle is generally caused by higher than normal air flow. This is an obvious symptom of cleaning TBs... not so obvious for hurricanes passing. With our now higher idle speeds, the PCV is releasing crankcase pressure as it is expected to do at 1500-2000rpm but is certainly not supposed to do at a normal idle - hence the temporary blocking (just let the PCV vent to atmosphere while you do the relearns).
(Btw, I tried all you did & also pulled a couple of injector plugs as mentioned in this thread all to no avail.)
Cheers,
Guv
09-27-2017, 05:40 PM
#67
Sorry it didn't work for you.
09-27-2017, 05:50 PM
#68
09-29-2017, 05:56 AM
#69
By reading various threads about this issue, I saw that most people who changed their throttle bodies at the dealership had the same issue afterwards. Apparently replacing the ECU/ECM was a solution for a couple of people so, I went ahead and ordered one (for an amazing price of $22 shipped, same year, same model, same transmission) and tried it today. After swapping the ECU's, the car would crank but not start. Is this normal? Do I need to go to the dealer to calibrate the keys or something? Or is the used ECU busted?
09-29-2017, 06:06 AM
#70
By reading various threads about this issue, I saw that most people who changed their throttle bodies at the dealership had the same issue afterwards. Apparently replacing the ECU/ECM was a solution for a couple of people so, I went ahead and ordered one (for an amazing price of $22 shipped, same year, same model, same transmission) and tried it today. After swapping the ECU's, the car would crank but not start. Is this normal? Do I need to go to the dealer to calibrate the keys or something? Or is the used ECU busted?
09-29-2017, 09:47 AM
#71
Yeah, I read about that now. Damn it, something else to pay for...
I got used throttle bodies from a 2015 Q40 with 15K miles, so I will try to installed them first and see if that fixes the problem. If not, I'll finally take the car to the dealer with both used throttle bodies and the ECU and see if they can figure it out.
I got used throttle bodies from a 2015 Q40 with 15K miles, so I will try to installed them first and see if that fixes the problem. If not, I'll finally take the car to the dealer with both used throttle bodies and the ECU and see if they can figure it out.
Last edited by ARG350Z; 09-29-2017 at 09:50 AM.
10-04-2017, 07:55 AM
#72
Update:
After replacing the ECU but not being able to turn the car on due to the NATS, VATS or however its called (I would have to reprogram the keys for the ECU to work), I put the old ECU back.
Today I replaced the OEM throttle bodies with a pair of Throttle bodies from a Q40 with 15K miles, and still, the car is not working correctly. I'm out of ideas.
Should I take the chance and take the car to get the keys reprogrammed? I feel that even though I would be taking a chance, if that works, I won't be forced to change the throttle bodies at the dealership.
Any other ideas?
After replacing the ECU but not being able to turn the car on due to the NATS, VATS or however its called (I would have to reprogram the keys for the ECU to work), I put the old ECU back.
Today I replaced the OEM throttle bodies with a pair of Throttle bodies from a Q40 with 15K miles, and still, the car is not working correctly. I'm out of ideas.
Should I take the chance and take the car to get the keys reprogrammed? I feel that even though I would be taking a chance, if that works, I won't be forced to change the throttle bodies at the dealership.
Any other ideas?
03-15-2019, 02:22 PM
#75
Long time lurker occasional poster
Ok I have done my research and there aren't many threads that seem to have been updated with what finally fixed this. Mine isn't fixed yet but will update this as it goes on. We will start with what has happened.
So to start it off I bought a stillen gen 3 intake. Decided to clean the maf, and the throttle bodies when I had the old intake taken off.
Got everything in place, and when I started my car up had a high idle. It was idling around 2000rpms then dropped to 1500rpms, and started the dreaded idle surge.
Went to my mechanic to get a relearn, since I couldn't get the pedal dance to work. He couldn't relearn it or figure out why, thought the throttle bodies looked fine. So went to the dealer to get them to do it. Said my throttle bodies were bad.
So I went up onto amazon and bought brand new throttle bodies. I installed them and went back to the dealer. They still can't program them. They told me to reinstall the old intake and bring it back, so they can diagnosis the issue.
The dealership thinks I either blew my cat or have bad o2 sensors.Now I haven't gotten a ses light at all, but it does smell like I am running rich. So I'm leaning/hoping there is a leak in the the gen 3, I have checked.
But that's where I am at will update how this goes. Oh and I haven't been driving it except to the dealer since this happened.
Ok I have done my research and there aren't many threads that seem to have been updated with what finally fixed this. Mine isn't fixed yet but will update this as it goes on. We will start with what has happened.
So to start it off I bought a stillen gen 3 intake. Decided to clean the maf, and the throttle bodies when I had the old intake taken off.
Got everything in place, and when I started my car up had a high idle. It was idling around 2000rpms then dropped to 1500rpms, and started the dreaded idle surge.
Went to my mechanic to get a relearn, since I couldn't get the pedal dance to work. He couldn't relearn it or figure out why, thought the throttle bodies looked fine. So went to the dealer to get them to do it. Said my throttle bodies were bad.
So I went up onto amazon and bought brand new throttle bodies. I installed them and went back to the dealer. They still can't program them. They told me to reinstall the old intake and bring it back, so they can diagnosis the issue.
The dealership thinks I either blew my cat or have bad o2 sensors.Now I haven't gotten a ses light at all, but it does smell like I am running rich. So I'm leaning/hoping there is a leak in the the gen 3, I have checked.
But that's where I am at will update how this goes. Oh and I haven't been driving it except to the dealer since this happened.
03-15-2019, 03:53 PM
#76
regarding people with high idle/idle surge issue w/ 07'350z....i stumbled across a tuner based in Concord CA named Eugene Turkov that found a way to fix the issue with the ECU. Decided to send my ECU out to him in hopes he could solve the issue. Based on his previous experience with the problem he said the latest firmware update will NOT fix the problem. The fix was upgrading the original ECU to a firmware from a similar 2008 model. My car is now running healthier than when i purchased it 4 years ago! Let me know if any of you need his info!
12-09-2019, 09:01 PM
#77
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regarding people with high idle/idle surge issue w/ 07'350z....i stumbled across a tuner based in Concord CA named Eugene Turkov that found a way to fix the issue with the ECU. Decided to send my ECU out to him in hopes he could solve the issue. Based on his previous experience with the problem he said the latest firmware update will NOT fix the problem. The fix was upgrading the original ECU to a firmware from a similar 2008 model. My car is now running healthier than when i purchased it 4 years ago! Let me know if any of you need his info!